This invention relates to a sensor that is integrated into a vehicle body member to measure payload.
Pick-up trucks and sport utility vehicles typically have a rear cargo area for transporting large items. These vehicles have maximum payload ratings that represent the maximum cargo weight that the vehicle can carry. Thus, it is important to know the weight of the payload because overloading can result in premature component wear and increased maintenance costs.
Often it is difficult to tell how much weight has been loaded onto a vehicle. Vehicles carry various types of cargo or payload in varying amounts. In order to avoid overload, it is important for a vehicle operator to know the payload weight at all times during the operation of the vehicle.
The most common method used for monitoring the payload weight is a scale. The vehicle is driven onto the scale and the weight of the vehicle plus the payload is measured while the vehicle is stationary. There are several drawbacks with this method. First, the scales are expensive and require continual maintenance to ensure proper calibration. Second, use of scales can be time consuming and inconvenient, as there is limited access to such scales.
Another method for monitoring the payload of a vehicle uses a force sensor, such as a load cell or pressure transducer, that is mounted onto an axle. This method is time consuming and expensive to install because it requires modifications the axle. The system components are also exposed to the external environment and can become damaged.
Thus, it is desirable to have an inexpensive system for determining the weight of a vehicle payload that continually monitors payload and which is easily installed, maintained. The system should be well protected, provide accurate measurements, and be easily incorporated into a pick-up truck or sport utility vehicle.
In a disclosed embodiment of this invention, a system for measuring a vehicle payload includes a body member supported on a vehicle frame and at least one sensor assembly mounted within the body member. The sensor assembly is used to generate a weight signal representative of weight of a payload supported on the body member. Preferably, the body member is formed from a plastic material and the sensor assembly is molded within the plastic material. The sensor is positioned over the vehicle frame such that the weight of the payload supported on the body member is directed through the frame and is easily measured by the sensor assembly.
In a preferred embodiment, the vehicle frame includes a first member for supporting one side of the body member and a second member, laterally spaced from the first member, for supporting an opposite side of the body member. A first sensor is molded within the body member and positioned over the first frame member and a second sensor is molded within the body member and positioned over the second frame member. The first sensor generates a first signal representative of a portion of the payload supported on the first frame member and the second sensor generates a second signal representative of a portion of the payload supported on the second frame member. A central processor receives the signals and transmits a weight indication signal to a driver. A warning device is activated if the payload weight exceeds a predetermined limit.
The method of assembling the payload measuring system into a vehicle includes the following steps. A cargo bed for transporting a vehicle payload is provided with a generally planar bottom member. At least one sensor is molded into the bottom member and the body member is mounted on a vehicle frame.
The subject system provides a simplified mechanism for measuring a vehicle payload that includes sensors that are easily integrated into a vehicle support member. The sensors are fixed relative to the support member to provide accurate measurements and are well protected from the possibility of external damage.